A gas turbine high-pressure compressor may include a centrifugal impeller. At the compressor exit and immediately behind (downstream of) the centrigual impeller the compressed air, also known as the “impeller backface air” may be used to pressurize an engine air system, referred to herein as the P3 Bleed Air System, as well as pressurizing nearby air-oil interfaces, such as those sealing adjacent bearing cavities. To drive such a system, sufficient pressures must be maintained in the impeller back face air.
An impeller baffle can be disposed downstream of the impeller backface can act as a diffuser, slowing the impeller backface air to locally increase the air pressure. However, despite the presence of an impeller baffle, the pressure at the impeller backface (and particularly at the tip of the impeller baffle) can still sometimes be too low.
Accordingly, there is a need to provide an improved design to address this potential susceptibility.